http://classiccampstoves.com/threads/optimus-99-intl-instructions-parts-list.20308/
The stoves self pressurize. Fill the tank with lighter petrol if you have no other clean fuel to hand (about two thirds full), use a bit of meths to prime the stove then when the meths is almost out gently open the control valve. You can prime with lighter fuel but it can get a bit sooty.
Caution: the key gets very hot if you leave it in place when running the stove, I take mine out until the flame needs adjusting or the stove turning off (turn the key clockwise to shut it down, fully anti clockwise operates the built in cleaning needle) LET THE STOVE COOL DOWN BEFORE OPENING THE FILLER CAP.
I paid £10.
Alas he hasnt anything else as interesting, mostly a load of East Europe and Portugese Primus pressure stove copies.
(And what I suspect is one of those big NZ Kelly kettles...But he wont part with that.)